This invention relates to locking devices for securing semitrailers, and more particularly to devices designed for releasable connection to the brake line or "glad hand" coupler of such trailers.
In the course of hauling loads by a semitrailer, it is not unusual for a driver to temporarily disconnect the tractor from the semitrailer. As such tractors and trailers typically utilize air brakes, separation of the semitrailer contemplates disengaging disconnecting an air hose from the brake line coupler on the semitrailer. When a trailer is left unattended, it is a well known practice to connect a locking device to the brake line coupler. One such locking device is disclosed in U.S. Pat. No. 4,226,103 to Strickland granted Oct. 7, 1980. Strickland shows a locking device 17 with a tongue 21, a flange having an opening 27, and a depressible key operated plunger 38. The tongue fits into a recess 34 of a glad hand coupler 3, with the opening 27 simultaneously surrounding a tongue 13 of the glad hand. Also, a plunger 38 is inserted into an opening 19 of the glad hand to lock the trailer. For similar purposes, U.S. Pat. No. 4,325,237 to Menzie granted Apr. 20, 1982 shows a brake line coupler lock having a key-operated cylinder 12. A pair of locking fingers at the bottom of the cylinder keep the cylinder in the glad hand until a key is used to free the cylinder.
More generally, U.S. Pat. No. 3,593,549 to Lakins granted July 20, 1971 shows a locking device for a pressure regulator. A locking pin 52 of the device has a head at one end, and a transverse opening at the other end for receiving a padlock. Also, U.S. Pat. No. 2,662,389 to McKitrick granted Dec. 15, 1953 shows a lock for an electrical switch, in which a cover plate 33 is retained by a pin inserted through holes in the cover plate. A padlock fits through an eye 40 of the pin to keep it in place.
These devices, while satisfactory in certain respects, do not adequately address the need for a locking device which is simple, reliable, and usable with brake line couplers of different sizes and shapes. The Strickland lock, for example, requires the glad hand to have particularly positioned tongue and opening to receive the locking device tongue. The lock described by Menzie is secured solely by relatively small fingers, and thus provides little resistance t determined tampering.
Therefore, it is an object of the present invention to provide a brake line coupling locking device that is inexpensive, relatively easy to manufacture, and reliable.
Another object of the invention is to provide a locking device suitable for a variety of brake line couplings of different sizes and shapes.
A further object of the invention is to provide a locking device that can utilize a conventional padlock to secure a semitrailer.
Yet another object of the invention is to provide a locking device for semitrailers which is virtually unaffected by bad weather or other unfavorable conditions.